Download Primary Succession - Summit School District

Primary Succession
• Succession is the step by step process where
one plant species establishes and is then out
competed by another until the area reaches the
climax community that can not be out
competed.
• Primary Succession starts from bare rock that
becomes exposed due to glaciers, geologic
uplift, and volcanoes.
• Soil must be established first before plants can
begin to inhabit an area which takes a long time.
• In many areas Lichen is the pioneer species
that first establishes on bare rocks and aids in
erosion.
Primary Succession
Secondary Succession
• Secondary succession takes place in an
area that already has an ecosystem
established but becomes disturbed by fire,
flood, logging, agriculture or any other
disturbance.
• After the disturbance the system will again
start moving toward the climax community.
• The size and type of disturbance
determines which stage of succession the
system will start over from and how long it
will take.
Secondary Succession
Mt. St. Helens
• http://www.youtube.com/watch?v=pGImks
oOwtU&feature=fvwrel
• http://www.youtube.com/watch?v=xP2dre
OI8gI
• http://www.youtube.com/watch?v=UK-hvgP2uY
Productivity
• Productivity- the rate of growth or
biomass increase in plants and animals.
• Gross Primary Productivity (GPP)- is
the total gain in energy or biomass per unit
area per unit time before any gets used for
respiration (R).
• Net Primary Productivity (NPP)- is the
energy/biomass that remains for the next
trophic level. (NPP=GPP-R)
Changes During Succession
• The size of organisms increases
• Simple food chains become more complex
• Soil depth, humus, water retention,
mineral content and cycling all increase.
• Biodiversity increases in early stages but
decreases as climax is reached
• NPP and GPP increase in early stages
and decrease as climax is reached
• Production:Respiration ratio gets closer to
1 as climax is reached